Most dynamic tasks performed by robots involve manipulation with high accelerations and application of forces to the environment. However, these tasks depend on the joint torques of the robot and reaction forces to the robot's base. For the case of manipulating objects with high accelerations, the reaction forces can be quite high. Applying forces to the environment also can produce high reaction forces and in addition require that all of the joint torques create the applied force. The production of these reaction forces and the dependence on joint torques can significantly limit the robot's performance.
Many conventional robots use counterweights to eliminate reaction forces generated by robot manipulation. However, counterweights add significant mass to the system and require the use of more powerful motors. Thus, the use of counterweights is undesirable for high-speed manipulation.
Conventional robots apply forces by relying on torques at each joint and reaction forces to the base. Therefore, the limiting factors for producing a force with a conventional robot are the weakest joint torque and the maximum allowable reaction force. These limitations significantly reduce the possible performance of robots